Adolescence is a key life phase in which physical activity levels and fitness appear to decline, yet is a very formative phase for future health. Emerging evidence now indicates the particular potency of so-called high-intensity interval training (HIIT) as an effective, expedient and possibly palatable option for adolescents. Partnering with schools and teachers to integrate HIIT into the curriculum represents a scalable and sustainable way to facilitate participation in HIIT. The aim of this study is to determine the preliminary efficacy and feasibility of embedding a teacher-delivered HIIT exercise programme within the school health and physical education curriculum at Year 8. A range of health, fitness, and academic measures will be used to determine effectiveness. This novel research would contribute towards the goal of understanding, maintaining and enhancing the health of our youth.